
Why, when thou hadst read Nature's mysterious manuscript, and then
Wast ready to reveal the truth it bears, Why art thou silent! Why shouldst thou be dead?
In "The Saturday Club" (1884), Oliver Wendell Holmes reminisced that he was rather a hottie:
The great professor, strong, broad-shouldered, square,
In life's rich noontide, joyous, debonair.

Personally, I don't see the attraction.
He married twice, and had three children. His second wife was Elizabeth Cabot, a scientist in her own right, who edited his papers and wrote a biography after his death.

During the 1906 San Francisco Earthquake, the statue of Agassiz at Stanford University toppled to the ground and was lodged head-first in concrete. There's a recreation of it at Richter's Burger Company at Universal Studios Orlando.
Agassiz's reputation has soured today because of his devotion to race science, that defunct 19th century amalgam of imperialism and prejudice that claimed that some races were more physically, emotionally, and spiritually evolved than others (guess which race got to be on top?).
Agassiz even subscribed to the theory of polygenism: the races originated from different pre-human groups, and so were biologically distinct, like separate species.
To help support his theory, in 1850 he arranged for a Z. T. Zealy of Columbia, South Carolina to take photographs of local slaves: nude, full frontal, side, and rear shots. Fifteen years later, he led an expedition to Brazil, where he photographed more slaves, frontal, side, and rear shots.
Although he disliked black people and "felt physically ill in their presence," Agassiz was delighted by what he interpreted as strong physiological differences that "proved" the two races to b different species with no common ancestor, the black far inferior to the white.
See "Black Bodies, White Science" on the U.S. Slave blog.
Today we look at these photographs with shock that anyone well-trained in the scientific method could have been so wrong, outrage that human beings were degraded in this way, and with a long-overdue erotic appreciation.
These men were strong, handsome, well-endowed, with friends and lovers whose bodies they touched, and who touched them. From a distance of 160 years, we can look back and appreciate masculine beauty where Agassiz and his audience saw only specimens.
But how are we to know that his audience didn't look at these photographs and see men?
The nude photos are on Tales of West Hollywood.